Nut punching apparatus

ABSTRACT

A nut punching apparatus has a striking punch ( 1 ), a caulking die ( 2 ), a nut feeding guide ( 10 ) having a punch passage ( 11 ) and a nut delivery opening ( 12 ) perpendicular to the passage, and a driving means ( 14 ) moving the guide along the punch. The nut ‘N’ fed through the opening is pushed into a transfer zone located ahead the punch ( 1 ) while the guide ( 10 ) is at its foremost position. This guide is retracted to its rearmost position to allow the punch to cooperate with the die ( 2 ) to punch the nut ‘N’ onto a metal plate ‘W’. The apparatus has a positioning pin ( 20 ) through the punch so that its fore end portion reciprocates taking a foraward position ahead the punch and a retracted position. The pin ( 20 ) penetrates a threaded bore of the nut ‘N’ at the transfer zone, such that the projected fore end portion of the pin ( 20 ) passing through the nut ‘N’ engages with a positioning aperture ( 30 ) formed in the metal plate ‘W’.

FIELD OF THE INVENTION

[0001] The present invention relates to a nut punching apparatus for useto strike the self-piercing nuts or the clinch nuts to a metal plateworkpiece, so as to fix them thereon.

BACKGROUND OF THE INVENTION

[0002] Heretofore, every workpiece such as a metal plate, panel or sheethas been positioned by abutting its edge against a stopper or the likewhen punching the self-piercing nuts or the clinch nuts to be attachedto said workpiece. This manner of positioning the workpieces may besuited to a case wherein a considerable number of them of the same shapeand dimentsion are manufactured sequentially. However, intricate andtime-spending operations have adversely been needed if many small lotsof various kinds of workpieces had to be handled by frequently adjustingarrangement of relevant members in the apparatus.

SUMMARY OF THE INVENTION

[0003] An object of the present invention made in view of this drawbackin the prior art is therefore to provide a novel type of nut punchingapparatus that can operate smoothly and quickly to accurately positionevery nut on any desired portion of the workpiece, to which the nut hasto be struck and fixed.

[0004] In order to achieve this object, the apparatus of the inventioncomprises a striking punch for thrusting a nut onto a metal plate, acaulking die facing the punch through the metal plate, a nut feedingguide having a punch passage and a nut delivery opening, the passageaccommodating the punch to be slidable therein, the opening extendingperpendicular to the passage, and a driving means for moving the nutfeeding guide fore and aft along the punch longitudinally thereof. Thesemembers are combined together such that the nut having advanced throughthe delivery opening will be pushed into a transfer zone located aheadthe fore end of the striking punch while the nut feeding guide is at itsforemost position, and such that the nut feeding guide will be retractedto its rearmost position so as to allow the striking punch to cooperatewith the caulking die to punch the nut onto the metal plate and tothereby attach it thereon. Further, the apparatus characteristicallycomprises a positioning pin that extends through the striking punchalong an axis thereof so that a fore end portion of the pin reciprocatesbetween its projected position ahead the fore end of the punch and itsretracted position behind this fore end, such that the pin penetrates athreaded bore of the nut which will have arrived at the transfer zoneahead the punch, whereby the projected fore end portion of the pinpassing through the nut is brought into engagement with a positioningaperture previously formed in the metal plate at its portion to whichthe nut will subsequently be punched and attached.

[0005] Preferably, the positioning pin may be held in a bore that isformed through the striking punch, and a pneumatic cylinder may bedisposed in a basal end of the punch so as to drive the pin toretractably project its fore end portion beyond the fore end of thepunch.

[0006] Also preferably, a pair of resilient pawls facing one another maybe disposed on opposite lateral sides of the punch fore end so that thenut having arrived at the transfer zone will be gripped with thesepawls.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a front elevation of a nut punching apparatus that isprovided in the present invention and shown in its vertical crosssection, wherein nuts are being fed towards a transfer zone;

[0008]FIG. 2 is a left side elevation of the apparatus shown in FIG. 1;

[0009]FIG. 3 is another front elevation of the apparatus shown in itsstatus ready for the striking of the nut;

[0010]FIG. 4 is a left side elevation of the apparatus shown in FIG. 3;

[0011]FIG. 5 is a further front elevation of the apparatus shown in itsstatus when positioning the nut; and

[0012]FIG. 6 is a still further front elevation of the apparatus shownin its status when punching the nut.

THE PREFERRED EMBODIMENTS OF THE INVENTION

[0013] Now some embodiments of the present invention will be described,referring to the drawings.

[0014]FIGS. 1 and 2 show the invention embodied in a nut punchingapparatus that comprises a striking punch 1 and a caulking die 2disposed to face the punch. In use of the apparatus, a workpiece ‘W’,i.e., a metal plate will intervene between the punch 1 and die 2, whichare designed to sequentially punch self-piercing nuts or clinch nuts(hereinafter referred to simply as ‘nuts’) onto the workpiece ‘W’.

[0015] The striking punch 1 has a basal end fixed on a back plate 4 bymeans of a punch holder 3. The back plate 4 is secured to a base of apressing machine (not shown) so that the punch 1 has an axis extendingvertically to have its fore end portion located upwards. A pair ofresilient pawls 5 and 5 (see FIGS. 2 and 4) facing one another aredisposed on opposite lateral sides of a fore end of the striking punch1. Each pawl 5 is a leaf spring connected by a screw, not shown, to theside of said punch side. In operation, a preceding one of the nuts ‘N’will arrive at a transfer zone that is located ahead the punch fore endso as to be gripped by and between the resilient pawls 5. A stopper 6defining an outer or downstream boundary for the transfer zone willserve to cause each nut to take its accurate position in said zone.

[0016] The caulking die 2 facing the punch 1 is mounted on a press ram(not shown) in the pressing machine. This die 2 located above thepressing punch stands precisely in an axial alignment therewith. Inoperation, the press ram will drive and carry the caulking die 2 inaxial direction towards and away from the striking punch 1.

[0017] A nut feeding guide 10 is operatively combined with the strikingpunch 1 so as to slide relative thereto in axial direction thereof. Apunch passage 11, that is a through-hole formed in the guide 10, willallow the punch to slide in axial direction. A nut delivery opening 12formed also in the nut feeding guide 10 extends perpendicularly to thepunch passage 11. A flexible hose 13 is connected to the deliveryopening 12 so that the nuts ‘N’ are successively supplied towards thepunch. In detail, the nuts will be sent one after another to thetransfer zone located ahead the punch's 1 fore end which is temporarilyat its position enclosed in the passage 11.

[0018] A pneumatic cylinder 14 fixed on the back plate 4 will drive thenut feeding guide 10 along the striking punch 1. A piston rod 15 of thedouble-action cylinder 14 extends in parallel with the punch and has enend secured to the feeding guide 10. Thus, this guide will move fore andaft (viz., up and down in the drawings) along the punch 1 and in unisonwith the piston rod 15. At a raised position of the feeding guide 10 asshown in FIGS. 1 and 2, the nuts ‘N’ advancing through the deliveryopening 12 will be delivered one by one to the transfer zone that isthen located ahead the punch fore end but retracted in the punch passage11.

[0019] The striking punch 1 included in the nut punching apparatus ofthe invention does further comprise a positioning pin 20. This pin isable to reciprocate along the axis of the punch so that its fore endportion 20 a can be projected forwards beyond or retracted backwardsbehind the fore end of striking punch 1. In detail, an axial bore 21accommodates therein the positioning pin 20 to slide in axial direction.A basal end 20 b of such a pin is connected to a piston 23 of apneumatic cylinder 22 that is disposed in the basal end portion of thepunch. A compression spring 24 fitted in the pneumatic cylinder 22always urges the fore end portion 20 a of the positioning pin 20 to sinkand descend into the axial bore 21. However, with a compressed air beingintroduced into the cylinder through an air passage 25, the piston 23will be forced upwards and forwards to lift the positioning pin 20.Consequently, its fore end portion 20 a will protrude beyond the foreend of the striking punch 1, against elastic force of the spring 24.

[0020] In use, the nut punching apparatus of the describe structure willoperate as follows. FIGS. 1 and 2 shows the nut feeding guide 10 at itsraised position wherein the preceding one of the nuts ‘N’ beingsuccessively fed through the hose 13 has just moved into the transferzone above the punch's fore end. The preceding nut ‘N’ thus dischargedfrom the nut delivery opening 12 to said zone located inside the passage11 is gripped with the pair of pawls 2 also located inside this passage.In this state, the fore end portion 20 a of the positioning pin 20 is atits retracted position behind the fore end of the striking punch 1, lestthe nut ‘N’ should be hindered from advancing smoothly.

[0021] Next, the nut feeding guide 10 will descend as seen in FIGS. 3and 4, being driven by the one or main pneumatic cylinder 14.Simultaneously with this motion, a compressed air will be charged to theother or supplementary pneumatic cylinder 22 to lift the positioning pin20 against the compression spring 24. In this state ready for punchingthe nut, the fore end portion 20 a of the pin is at its positionextended above the fore end of the striking punch 1. This means that thesaid end portion 20 a protrudes up and out through the threaded bore ofnut ‘N’ being held in place by the stopper 6 and pawls 5. On the otherhand, a positioning aperture 30 has previously been formed in theworkpiece ‘W’ at its portion to which the nut ‘N’ has to be attached.

[0022] The workpiece will then be placed between the caulking die 2 andthe striking punch 1 that has been made ready for punching the nut, andits position will be adjusted by engaging the aperture 30 with theprojected fore end 20 a of the positioning pin 20 (see FIG. 5).

[0023] Subsequently, the caulking die 2 will descend as shown in FIG. 6to cooperate with the punch 1 to forcibly grip between them theworkpiece ‘W’, with a force enough for it to be bitten with the nut ‘N’.Upon fixation of the nut on the workpiece in this manner, the caulkingdie 2 will ascend to return both the positioning pin 20 and the nutfeeding guide 10 to their home positions shown in FIG. 1.

[0024] In the illustrated embodiment, the striking punch 1 located belowthe caulking die 2 ascending and descending does stand still. A reversedarrangement may be employed instead, wherein the caulking die 2 islocated below the punch 1 which will be driven up and down in this case.

[0025] It will now be apparent that in the invention the positioning pinincorporated in the striking punch penetrates the threaded bore of eachnut that has been placed in the transfer zone above the punch for end.The fore end portion of such a pin will remain engaged with apositioning aperture formed in and at each desired point of theworkpiece, during the subsequent punching process. Now, the positioningoperation can be done more simply and quickly on one hand, and the nutscan be punched exactly into all the desired points in the workpiece onthe other hand.

1. A nut punching apparatus comprising: a striking punch for thrusting anut onto a metal plate; a caulking die facing the punch through themetal plate; a nut feeding guide having a punch passage and a nutdelivery opening; the passage accommodating the punch to be slidabletherein; the opening extending perpendicular to the passage; and adriving means for moving the nut feeding guide fore and aft along thepunch longitudinally thereof, such that the nut having advanced throughthe delivery opening is pushed into a transfer zone located ahead a foreend of the striking punch while the nut feeding guide is at its foremostposition, and such that the nut feeding guide is retracted to itsrearmost position so as to allow the striking punch to cooperate withthe caulking die to punch the nut onto the metal plate, the apparatusfurther comprising a positioning pin that extends through the strikingpunch along an axis thereof so that a fore end portion of the pinreciprocates between its projected position ahead the fore end of thepunch and its retracted position behind this fore end, such that the pinpenetrates a threaded bore of the nut which has arrived at the transferzone ahead the punch, whereby the projected fore end portion of thepositioning pin passing through the nut is brought into engagement witha positioning aperture previously formed in the metal plate at itsportion to which the nut is to be punched.
 2. A nut punching apparatusas defined in claim 1 , wherein the positioning pin is held in a borethat is formed through the striking punch, and a pneumatic cylinder isdisposed in a basal end of the punch so as to drive the pin toretractably project its fore end portion beyond the fore end of thepunch.
 3. A nut punching apparatus as defined in claim 1 or 2 , whereina pair of resilient pawls facing one another are disposed on oppositelateral sides of the fore end of the punch so that the nut havingarrived at the transfer zone is gripped with these pawls.